[Antimicrobial resistance monitoring of gram-negative bacilli isolated from 15 teaching hospitals in 2014 in China].

Objective: To investigate the current situation of antimicrobial resistance of nosocomial gram-negative bacilli in 2014 in China.

Methods: About 1 430 consecutive and non-repetitive strains of gram-negative bacilli were isolated from 15 teaching hospitals from March to August in 2014. All of these isolates were sent to the central laboratory for reidentification and susceptibility testing. The minimal inhibitory concentration (MIC) of meropenem and other antibacterial agents were determined by agar dilution method. The data were analyzed by using WHONET-5.6 software.

Results: The activity of antimicrobial agents against Enterobacteriaceae was listed as followings in descending order of susceptibility: meropenem (94.7%, 913/964), amikacin (94.4%, 910/964), imipenem (88.5%, 853/964), ertapenem (87.8%, 847/964), piperacillin-tazobactam (87.2%, 841/964), cefoperazone-sulbactam (86.7%, 836/964), polymyxin B (77%, 742/964), cefepime (74.5%, 718/964), cefiazidime (71.8%, 692/964), levofloxacin (71.1%, 685/964), ciprofloxacin (67.7%, 653/964), minocyline (64.2%, 619/964), ceftriaxone (56.8%, 548/964), cefotaxime (55.8%, 538/964), cefoxitin (45.5%, 439/964). The prevalence of extended-spectrum beta-lactamases (ESBLs) was 57.6% (114/198) in E. coli and 24.6% (49/199) in Klebsiella pneumonia. The sensitivity of E. coli to carbapenems, amikacin, piperacillin-tazobactam, polymyxin B and cefoperazone-sulbactam was all over 80%. However, over 60% E. coli strains were resistant to ciprofloxacin, levofloxacin, ceftriaxone and cefotaxime. Polymyxin B was the most susceptible antibiotic to Klebsiella pneumoniae (99.5% sensitive), followed by amikacin (89.9%), meropenem (86.4%), imipenem (86.4%) and piperacillin-tazobactam (81.9%), while ceftriaxone (60.8%) and cefotaxime (59.8%) were less sensitive. The activity of antimicrobial agents against E. cloacae, E. aerogenes and Citrobacter freundii was listed as followings in descending order of susceptibility: meropenem (96.1%-97.4%), imipenem (95.1%-97.1%), polymyxin B (92.6%-99.0%), cefoperazone/sulbactam (87.3%-92.6%), ertapenem (85.6%-93.3%), piperacillin-tazobactam (65.0%-89.8%). The susceptibility rates of meropenem, cefoperazone-sulbactam, piperacillin-tazobactam, cefepime to Proteus mirabilis, Proteus vulgaris and Morganella morganii were all more than 90.0%. The most active agents against Pseudomonas aeruginosa were polymyxin B (99.5%), followed by amikacin (92.0%) and ciprofloxacin (82.1%). A. baumanni was most susceptible to polymyxin B (99.0%), while resistant to imipenem, meropenem and cefoperazone-sulbactam (29.2%, 28.2% and 29.7% respectively), mediate to minocycline (67.0%). Based on the new breakpoints for cefepime to Enterobacteriaceae, the drug susceptible rates decreased 25.8% to E. coli and 14.7% to E. cloacae.

Conclusions: Carbapenems remain high susceptibility against Enterobacteriaceae, however carbapenem-resistant Enterobacteriaceae (CREs) have emerged. The sensitivity of Enterobacteriaceae against cefepime has been decreased according to the new breakpoint. Multi-drug resistant A. baumanni should be monitored persistently.